Without using SAN-to-SAN replication, how does data synchronization occur across subnets in a multi-subnet AlwaysOn (AVG) configuration? I want to setup a separate VLAN (replica lan) to synchronize data between three nodes (2 sync in DC1, and 1 async in DC2), but concerned there will need to be additional routing resources to make that possible.


There is no easy answer for this, you will have to go through the entire process from scratch and preferably do it several times so you know exactly what to expect, then focus on monitoring it. This is well documented though and you should start with a search engine query to get familiar with it.

Edwin is a resident HA expert in the SQL Server community and he has great articles on AG's. Here is one about your method. It's too long to post here or shrink, but your answer is to google 'multi subnet ag sql server' or something to that effect. That will lead you to one of several posts, starting a multi part series by Edwin: SQL Server 2012 Multi-Subnet Cluster Part 1

  • Sorry for not being more clear. My question is more along the lines of routing the log block traffic and not so much being able to connect to the listeners during failover. I have Team NIC 1(server network) and Team NIC 2(replica network). Endpoints are bound to replica network, listeners server network. I want a deeper understanding of how that traffic routes to the second datacenter when the server only has one gateway configured, if that is even possible. Examples I have seen so far either have shown how to configure the replica network, or to configure multisubnet, but not both. Thanks – Smiley77 Jan 20 '16 at 22:16
  • You don't configure routing of anything in availability groups for the network layer. The best you can do is tie it to an IP. The rest of the work is done by windows and your physical networking configuration. My answer would be: How do normal TCP/IP packets get routed from that network - it'll be routed the same exact way. – Sean Gallardy Jan 21 '16 at 6:11

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